VANCOUVER — Construction of the Trans Mountain pipeline expansion will likely be delayed due to detailed route hearings, outstanding provincial permits and Indigenous court challenges, says a report from environmental group Stand.earth.

The report argues that the Crown corporation that owns the project faces bigger construction challenges than it has openly acknowledged and is unlikely to complete it within a planned three-year timeline.

Many details of construction are publicly available, but they are complex and buried on the website of the Canadian Energy Regulator, formerly the National Energy Board, Tzeporah Berman of Stand.earth told a news conference Wednesday.

"The lack of transparency about the impacts and timeline of the potential construction of the Trans Mountain pipeline has been worse since the federal government bought it," she said.

"Canadian taxpayers who are the ones paying for this multibillion-dollar project have a right to know the impacts that construction will have on communities and the environment."

The Canadian Energy Regulator revoked all previous route approvals in July and required Trans Mountain Corp. to file new notices of its proposed route. Residents, municipalities and Indigenous groups may then file statements of opposition and the regulator decides on a segment-by-segment basis whether to hold detailed route hearings.

The environmental group's report says statements of opposition have been filed in every major segment and hearings are likely to be considered for the Fraser River crossing, Burnaby Mountain Tunnel, and areas where schools, homes and municipal water supplies could be affected.

Stand.earth adds the project needs 1,187 permits from British Columbia and as of June, the province was reviewing 658 permits, while applications for a further 243 have not made yet.

It also notes that the Federal Court of Appeal has granted six Indigenous groups leave to challenge the federal government's approval of the expansion. The court called for narrowly focused hearings with a strict timeline.

Trans Mountain has said that it is proceeding with the project in a phased approach, starting construction where it has received permits, and that it has begun work on its terminals in Burnaby and plans to start work in the Greater Edmonton area soon.

The Crown corporation said it expects the project to be operational by mid-2022.

These work camps or "man camps," temporary housing facilities for predominantly male workers, will be established in at least five B.C. communities during construction. The recent report following the national inquiry into missing and murdered Indigenous women linked such camps to higher rates of violence against Indigenous women.

The group reiterates concerns raised by the City of Burnaby about the potential impacts of earthquakes or fires on the project's local infrastructure. It says a diluted bitumen spill would pose health risks including cardiovascular or respiratory illnesses, reproductive disorders and cancers.

The report says the corporation's plans to cross the Coquihalla River using "cut and cover" techniques, in which a trench is excavated and backfilled after pipe is laid, are disruptive for fish species, while a rupture of its crossing in the Fraser River would harm nearby residents' drinking water and local economies.

It also says the expanded Westridge Marine Terminal would obstruct 30 per cent of the width of Burrard Inlet and increase the risk of collisions between tankers.

Trans Mountain said in a statement Wednesday that after seven years of consultation, design, studies and planning, it is confident it have considered, addressed and effectively mitigated the concerns and risks raised in Stand.earth's report.

"The re-start of construction on the expansion project demonstrates that Canada can have a healthy, rigorous discussion about issues and also ensure a project that has followed every process and obtained the necessary approvals gets built," it said.

"We're confident that we will build and operate the expansion safely, responsibly and in respect of communities, Indigenous groups and the environment."

The Liberal government, which purchased the pipeline and related assets for $4.5 billion, has argued the expansion is in the national interest and said it is investing in ocean protection and climate change initiatives at the same time.

However, Berman told reporters that it was impossible to fight climate change while increasing the flow of oil.

"When your house is on fire, you don't add more fuel. The Trans Mountain pipeline is more fuel and presents serious safety, security and climate risks."

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